Comparison of receptors for Clostridium perfringens type A and cholera enterotoxins in isolated rabbit intestinal brush border membranes

Abstract

The rabbit intestinal brush border membrane (BBM) receptors for Clostridium perfringens type A (CPE) and cholera (CT) enterotoxins were compared. Initial studies characterized binding of 125I-CPE to isolated BBMs as specific, saturable, and irreversible. BBMs appear to contain a single type of CPE binding site. Protease pretreatment of BBMs strongly reduced subsequent specific binding of 125I-CPE but not 125I-CT, while neuraminidase pretreatment had little effect on binding of either enterotoxin. Proteases did not significantly release pre-bound 125I-CPE. Preincubation of CPE with an affinity-purified preparation containing a previously identified (Biochem. Biophys. Res. Commun. 112, 1099-105) CPE-binding protein resulted in reduced specific binding of 125I-CPE and an inhibition of CPE biologic activity. Similar experiments showed that CPE-binding protein had no effect on CT binding or biologic activity. Gangliosides had no significant effect on specific binding or biologic activity of CPE but reduced CT binding and biologic activity. Lipids, including gangliosides, separated by thin layer chromatography specifically bound CT but not CPE. Preincubation of BBMs with CT did not reduce subsequent binding of 125I-CPE; conversely, prebound CPE did not affect subsequent 125I-CT binding. These results strongly suggest that CPE does not share the CT BBM receptor ganglioside GM1, and support a role for the CPE-binding protein in CPE binding.